A typical alternating-current surface discharge panel used as a plasma display panel (hereinafter, simply referred to as “panel”) has a large number of discharge cells that are formed between a front plate and a rear plate facing each other. The front plate has the following elements:                a plurality of display electrode pairs, each formed of a scan electrode and a sustain electrode, disposed on a front glass substrate parallel to each other; and        a dielectric layer and a protective layer formed so as to cover the display electrode pairs. The rear plate has the following elements:        a plurality of parallel data electrodes formed on a rear glass substrate;        a dielectric layer formed so as to cover the data electrodes;        a plurality of barrier ribs formed on the dielectric layer parallel to the data electrodes; and        phosphor layers formed on the surface of the dielectric layer and on the side faces of the barrier ribs.        
The front plate and the rear plate face each other such that the display electrode pairs and the data electrodes three-dimensionally intersect, and are sealed together. A discharge gas containing xenon in a partial pressure ratio of 5%, for example, is sealed into the inside discharge space. Discharge cells are formed in portions where the display electrode pairs face the data electrodes. In a panel having such a structure, gas discharge generates ultraviolet light in each discharge cell. This ultraviolet light excites the red (R), green (G), and blue (G) phosphors so that the phosphors emit the corresponding colors for color display.
As a driving method for the panel, a subfield method is typically used. In the subfield method, one field period is divided into a plurality of subfields, and gradations are displayed by the combination of the subfields where light is emitted.
Each subfield has an initializing period, an address period, and a sustain period. In the initializing period, an initializing waveform is applied to the respective scan electrodes so as to cause an initializing discharge in the respective discharge cells. This initializing discharge forms wall charge necessary for the subsequent address operation in the respective discharge cells and generates priming particles (excitation particles for causing an address discharge) for stably causing the address discharge.
In the address period, a scan pulse is sequentially applied to the scan electrodes (hereinafter, this operation being also referred to as “scanning”). Further, an address pulse corresponding to a signal of an image to be displayed is selectively applied to the data electrodes (hereinafter, these operations being also generically referred to as “addressing”). Thus, an address discharge is selectively caused between the scan electrodes and the data electrodes so as to selectively form wall charge.
In the sustain period, a sustain pulse is alternately applied to display electrode pairs, each formed of a scan electrode and a sustain electrode, at a predetermined number of times corresponding to a luminance to be displayed. Thereby, a sustain discharge is selectively caused in the discharge cells where the address discharge has formed wall charge, and thus causes light emission in the discharge cells (hereinafter, causing light emission in a discharge cell being also referred to as “lighting”, causing no light emission in a discharge cell as “non-lighting”). In this manner, an image is displayed in the display area of the panel.
In this subfield method, the following operations, for example, can minimize the light emission unrelated to gradation display and thus improve the contrast ratio. In the initializing period of one subfield among a plurality of subfields, an all-cell initializing operation for causing a discharge in all the discharge cells is performed. In the initializing periods of the other subfields, a selective initializing operation for causing an initializing discharge selectively in the discharge cells having undergone a sustain discharge is performed.
With a recent increase in the screen size and definition of a panel, the plasma display device is requested to have enhanced image display quality. However, a difference in drive impedance between display electrode pairs causes a difference in the voltage drop in drive voltage. This can produce a difference in emission luminance even with image signals having an equal luminance, in some cases.
To address this problem, the following technique is disclosed (see Patent Literature 1, for example). In this technique, the lighting patterns in the subfields in one field are changed when the drive impedance changes between display electrode pairs.
Another technique is disclosed to reduce an image persistence phenomenon in a panel and uniformize the display luminance in the respective discharge cells (see Patent Literature 2, for example). In this technique, an overlapping period is set such that a time period during which a sustain pulse applied to one electrode of a display electrode pair rises is overlapped with a time period during which a sustain pulse applied to the other electrode of the display electrode pair falls. Further, the overlapping period is changed according to the light-emitting rate detected in the light-emitting rate detecting circuit.
On the other hand, with an increase in the screen size and definition of a panel, the drive impedance of the panel tends to increase. Thus, even among the discharge cells formed on one display electrode pair, the difference in the voltage drop in drive voltage tends to increase between a discharge cell positioned nearer to the driving circuit and a discharge cell positioned farther from the driving circuit.
However, with the technique disclosed in Patent Literature 1, it is difficult to reduce the difference in emission luminance based on the difference in the voltage drop in drive voltage between a discharge cell positioned nearer to the driving circuit and a discharge cell positioned farther from the driving circuit on one display electrode pair.
The increase in the screen size and definition of a panel increases the interelectrode capacitance of the panel. The increased interelectrode capacitance increases reactive power, which is uselessly consumed without contributing to light emission when the panel is driven. This is one of the causes for increasing power consumption.
In a panel of which drive impedance is increased by the increase in the screen size and definition, a waveform distortion, such as ringing, is likely to occur in the driving waveforms. This is likely to increase variations in discharge, and thus cause variations in luminance, which is called luminance unevenness.